During hydrocarbon production from subsurface formations, efficient control of the movement of unconsolidated formation particles into the wellbore, such as sand or other debris, has always been a pressing concern. Such formation movement commonly occurs during production from completions in loose sandstone or following the hydraulic fracture of a subterranean formation. Formation movement can also occur suddenly in the event a section of the wellbore collapses, thereby circulating significant amounts of particulates and fines within the wellbore. Production of these unwanted materials can cause numerous problems while extracting oil and gas from subterranean formations. For example, producing formation particles can plug production tubing and subsurface flow lines, and can result in the erosion of casing, downhole equipment, and surface equipment. These problems lead to high maintenance costs and unacceptable well downtime.
Numerous methods have been utilized to control the production of unconsolidated formation particles during production. Sand control screen assemblies, for instance, are used to regulate and restrict the influx of formation particles. A typical sand control screen assembly generally includes a wire a wrapped screen or single or multi-layer wire mesh screen positioned about a perforated base pipe. In operation, the sand control screen assembly allows fluids to flow therethrough but prevents the influx of particulate matter of a predetermined size and greater.
Another method to control and otherwise reduce the production of unconsolidated formation particles during production is to gravel pack the wellbore annulus defined between a sand control screen assembly and the wellbore wall. In a gravel-packing operation, a gravel slurry substantially comprising a fluid and particulate matter (e.g., engineered gravel or sand) is pumped into the wellbore annulus and the particulate matter is sized such that it is prevented from penetrating the sand screen. Upon drawing the fluid out of the gravel slurry through the sand screens, the particulate matter remains and is converted into a fluid porous sand pack that prevents the passage of formation sand into the base pipe.
Sand control screen assemblies, however, often have “dead spaces” extending along various axial lengths of the base pipe and where there is no fluid flow through the wall of the base pipe. A dead space, for instance, exists at the ends of connecting base pipes where each base pipe provides an area on its exterior for handling the base pipes in making up the connection. Another type of dead space may exist between axially adjacent screen sections that are coupled with an impermeable shroud that interposes the two screen sections. Since there is no fluid flow into the base pipe at these dead spaces, a void or poor quality gravel pack often results across dead spaces. This can result in portions of the sand pack settling in the dead spaces during production operation, and thereby exposing portions of adjacent sand screens. As will be appreciated, an exposed sand screen is susceptible to erosion and abrasion caused by inflowing fluid and debris, which could ultimately damage the sand screen and frustrate its operative purpose.